Yes, the Panny weight demo makes the point, but is very vulnerable to further criticisms, too.

Not only the geeky rathole about 'equivalence' (which I'm not going near), but more significantly the equating of the 100-300 f4-5.6 with a 600mm f4. Focusing performance of those two for anything moving differs like night and day, so they should have included the 100-400, which does at least enable you to get the shot!

I use a 6.5mm Meike fisheye, with a 190 deg. field of view. The 4mm Laowa should have the advantage of projecting a fully circular image on MFT, whereas the Meike (originally designed for APS) is slightly clipped at top and bottom of the frame. This clipping has rarely bothered me, as it usually only cuts plain sky and feet! The image quality of the Meike is very good and the price only £125, so the Laowa will have to be very special to compete.